U.S. patent number 8,785,914 [Application Number 12/872,304] was granted by the patent office on 2014-07-22 for piezoelectric nanowire structure and electronic device including the same.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Duk-Hyun Choi, Jae-Young Choi. Invention is credited to Duk-Hyun Choi, Jae-Young Choi.
United States Patent |
8,785,914 |
Choi , et al. |
July 22, 2014 |
Piezoelectric nanowire structure and electronic device including
the same
Abstract
A piezoelectric nanowire structure includes a base substrate, a
plurality of piezoelectric nanowires disposed on the base
substrate, and a piezoelectric organic material layer disposed on
the base substrate and covering the plurality of piezoelectric
nanowires.
Inventors: |
Choi; Duk-Hyun (Hwaseong-si,
KR), Choi; Jae-Young (Suwon-si, KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Choi; Duk-Hyun
Choi; Jae-Young |
Hwaseong-si
Suwon-si |
N/A
N/A |
KR
KR |
|
|
Assignee: |
Samsung Electronics Co., Ltd.
(KR)
|
Family
ID: |
43924426 |
Appl.
No.: |
12/872,304 |
Filed: |
August 31, 2010 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20110101315 A1 |
May 5, 2011 |
|
Foreign Application Priority Data
|
|
|
|
|
Oct 30, 2009 [KR] |
|
|
10-2009-0104648 |
|
Current U.S.
Class: |
257/40; 438/50;
257/E51.001; 257/E21.002 |
Current CPC
Class: |
H01L
41/183 (20130101); B82Y 10/00 (20130101); H01L
29/0665 (20130101); H01L 29/0676 (20130101); H01L
41/113 (20130101); H02N 2/18 (20130101) |
Current International
Class: |
H01L
51/00 (20060101); H01L 21/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2008-047693 |
|
Feb 2008 |
|
JP |
|
10-2007-0031700 |
|
Mar 2007 |
|
KR |
|
Other References
Lu et al. "Piezoelectric Nanogenerator Using p-Type ZnO Nanowire
Arrays" Nano Letters 2009, 9, 1223-1227. Date of publication: Feb.
11, 2009. cited by examiner .
Xi et al. "Growth of ZnO nanotube arrays and nanotube based
piezoelectric nanogenerators" Journal of Materials Chemistry 2009,
19, 9260-9264. Date of publication: Aug. 29, 2009. cited by
examiner .
Hillman et al. "Time-Temperature Superposition for Viscoelastic
Properties of Regioregular Poly(3-hexylthiophene) Films" J. Am.
Chem. Soc. 2005, 127, 3817-3824. Date of online publication: Mar.
1, 2005. cited by examiner.
|
Primary Examiner: Bohaty; Andrew K
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
What is claimed is:
1. An electronic device comprising: a first electrode and a second
electrode spaced apart from each other; a plurality of
piezoelectric nanowires disposed on the first electrode; and a
piezoelectric organic material layer disposed between the second
electrode and the plurality of piezoelectric nanowires, wherein the
piezoelectric organic material layer comprises a composite material
including an organic material, the organic material including one
of polyvinylidene fluoride ("PVDF"), poly(3-hexylthiophene) (P3HT),
polyaniline, polypyrrole, poly(p-phenylene vinylene) ("PPV"),
polyvinylene, polyacetylene, polythiophene, derivatives thereof,
and combinations thereof, wherein the piezoelectric nanowires
comprise an n-type semiconductor, and the piezoelectric organic
material layer comprises a p-type organic semiconductor generating
electron-hole excitons by adsorbing light.
2. The electronic device of claim 1, wherein at least one of the
first electrode and the second electrode has flexibility and is
deformable by an applied pressure.
3. The electronic device of claim 2, further comprising a first
substrate contacting the first electrode, and a second substrate
contacting the second electrode, wherein at least one of the first
substrate and the second substrate has flexibility and is
deformable by the applied pressure.
4. The electronic device of claim 1, wherein at least one of the
first electrode and the second electrode comprises a transparent
material.
5. The electronic device of claim 1, wherein the nanowires comprise
zinc oxide (ZnO), lead zirconate titanate ("PZT"), barium titanate
(BaTiO.sub.3), lead titanate (PbTiO.sub.3), aluminum nitride
("AlN"), gallium nitride ("GaN"), or silicon carbide ("SiC").
6. The electronic device of claim 1, wherein the first electrode
comprises a plurality of first sub-electrodes, the second electrode
comprises a plurality of second sub-electrodes, the plurality of
first sub-electrodes is spaced apart from each other in a second
direction, and each of the first sub-electrodes extends along a
first direction, and the plurality of second sub-electrodes is
spaced apart from each other in the first direction, and each of
the second sub-electrodes extends along the second direction which
is perpendicular to the first direction.
7. The electronic device of claim 1, further comprising a
connecting part electrically connecting the first electrode and the
second electrode, and a storing part electrically connected to the
connecting part.
8. The electronic device of claim 1, further comprising a
connecting part electrically connecting the first electrode and the
second electrode, and a DC converter electrically connected to the
connecting part.
9. The electronic device of claim 1, wherein the first electrode
includes the same material as in the piezoelectric nanowires.
10. An electronic device comprising: a first electrode and a second
electrode spaced apart from each other; a plurality of
piezoelectric nanowires disposed on the first electrode; and a
piezoelectric organic material layer disposed between the second
electrode and the plurality of piezoelectric nanowires, wherein the
piezoelectric nanowires comprise an n-type semiconductor and have
an etched surface, and the piezoelectric organic material layer
comprises a p-type organic semiconductor generating electron-hole
excitons by adsorbing light.
11. An electronic device comprising: a first electrode and a second
electrode spaced apart from each other; a plurality of
piezoelectric nanowires disposed on the first electrode; and a
piezoelectric organic material layer disposed between the second
electrode and the plurality of piezoelectric nanowires, wherein the
piezoelectric nanowires comprise an n-type semiconductor, the
piezoelectric organic material layer comprises a p-type organic
semiconductor generating electron-hole excitons by adsorbing light,
and wherein the piezoelectric organic material layer is disposed in
an entire area between adjacent protruding portions of
piezoelectric nanowires.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to Korean Patent Application No.
10-2009-0104648 filed on Oct. 30, 2009, and all the benefits
accruing therefrom under 35 U.S.C. .sctn.119, the entire content of
which is incorporated herein by reference.
BACKGROUND
1. Field
Provided is a piezoelectric nanowire structure and an electronic
device including the same.
2. Description of the Related Art
In order to realize down-sizing and high performance of electronic
devices, nanoscale devices are being advanced. This requires
developing techniques for forming nanowires in order to provide the
nanoscale devices. A nanowire is an ultrafine line having a
cross-sectional diameter of about several nanometers (nm) to about
several hundred nanometers (nm). In addition, the length of the
nanowire may be grown to about several tens or several thousand
times or more of the diameter.
The nanowire may have different electrical, chemical, physical, and
optical characteristics from general characteristics shown in the
conventional bulk structure. By using the molecular characteristics
of nanowires together with the characteristics of a bulk structure,
it is possible to accomplish finer and more integrated devices.
Nanowires may be applied to various fields, such as for lasers,
transistors, memories, sensors, and the like.
However, the piezoelectric nanowires are easily damaged by external
force due to the ultrafine lines having a cross-sectional area of a
very small diameter.
In addition, there has been a tendency to produce mobile electronic
devices that are down-sized, portable, and integrated with various
functions. In order to supply electric power to the mobile
electronic devices, a battery having appropriate capacity is
required. However, the capacity of a battery supplying electric
power is behind the trend of integrating these devices with various
functions. Accordingly, a subsidiary battery is required. That is,
a subsidiary battery urgently needs to be developed as a power
source that is capable of being wirelessly charged.
SUMMARY
A piezoelectric nanowire structure that is not easily damaged by
external force, and an electronic device using the same are
provided.
Provided is a piezoelectric nanowire structure including a base
substrate, a plurality of piezoelectric nanowires disposed on the
base substrate, and a piezoelectric organic material layer disposed
on the base substrate and covering the plurality of piezoelectric
nanowires.
Provided is an electronic device including a first electrode and a
second electrode spaced apart from each other, a plurality of
piezoelectric nanowires disposed on the first electrode, and a
piezoelectric organic material layer disposed between the first
electrode and the second electrode and covering the plurality of
piezoelectric nanowires.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other advantages and features of this disclosure will
become more apparent by describing in further detail embodiments
thereof with reference to the accompanying drawings, in which:
FIG. 1A is a cross-sectional view showing an embodiment of a
piezoelectric nanowire structure, according to the invention.
FIG. 1B is a cross-sectional view showing an embodiment of
operation of the piezoelectric nanowire structure of FIG. 1A.
FIG. 2A is a cross-sectional view showing another embodiment of a
piezoelectric nanowire structure, according to the invention.
FIG. 2B is a cross-sectional view showing an embodiment of
operation of the piezoelectric nanowire structure of FIG. 2A.
FIG. 3A a cross-sectional view showing another embodiment of a
piezoelectric nanowire structure, according to the invention.
FIG. 3B is a cross-sectional view showing another embodiment of a
piezoelectric nanowire structure, according to the invention.
FIG. 4 is a cross-sectional view schematically showing an
embodiment of an electrical energy generating device including the
piezoelectric nanowire structure, according to the invention.
FIG. 5 is a cross-sectional view theoretically showing an
embodiment of a first operation of the electrical energy generating
device shown in FIG. 4.
FIG. 6 is a cross-sectional view theoretically showing an
embodiment of a second operation of the electrical energy
generating device shown in FIG. 4.
FIG. 7 is an exploded perspective view of an embodiment of an
electronic device including a piezoelectric nanowire structure,
according to the invention.
DETAILED DESCRIPTION
The invention is described more fully hereinafter with reference to
the accompanying drawings, in which embodiments of the invention
are shown. This invention may, however, be embodied in many
different forms and should not be construed as limited to the
embodiments set forth herein. Rather, these embodiments are
provided so that this disclosure will be thorough and complete, and
will fully convey the scope of the invention to those skilled in
the art. In the drawings, the size and relative sizes of layers and
regions may be exaggerated for clarity.
It will be understood that when an element or layer is referred to
as being "on" or "connected to" another element or layer, the
element or layer can be directly on or connected to another element
or layer or intervening elements or layers. In contrast, when an
element is referred to as being "directly on" or "directly
connected to" another element or layer, there are no intervening
elements or layers present. Like numbers refer to like elements
throughout. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second,
third, etc., may be used herein to describe various elements,
components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited
by these terms. These terms are only used to distinguish one
element, component, region, layer or section from another region,
layer or section. Thus, a first element, component, region, layer
or section discussed below could be termed a second element,
component, region, layer or section without departing from the
teachings of the invention.
Spatially relative terms, such as "lower," "upper" and the like,
may be used herein for ease of description to describe the
relationship of one element or feature to another element(s) or
feature(s) as illustrated in the figures. It will be understood
that the spatially relative terms are intended to encompass
different orientations of the device in use or operation, in
addition to the orientation depicted in the figures. For example,
if the device in the figures is turned over, elements described as
"lower" relative to other elements or features would then be
oriented "upper" relative to the other elements or features. Thus,
the exemplary term "lower" can encompass both an orientation of
above and below. The device may be otherwise oriented (rotated 90
degrees or at other orientations) and the spatially relative
descriptors used herein interpreted accordingly.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
Embodiments of the invention are described herein with reference to
cross-section illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of the
invention. As such, variations from the shapes of the illustrations
as a result, for example, of manufacturing techniques and/or
tolerances, are to be expected. Thus, embodiments of the invention
should not be construed as limited to the particular shapes of
regions illustrated herein but are to include deviations in shapes
that result, for example, from manufacturing.
For example, an implanted region illustrated as a rectangle will,
typically, have rounded or curved features and/or a gradient of
implant concentration at its edges rather than a binary change from
implanted to non-implanted region. Likewise, a buried region formed
by implantation may result in some implantation in the region
between the buried region and the surface through which the
implantation takes place. Thus, the regions illustrated in the
figures are schematic in nature and their shapes are not intended
to illustrate the actual shape of a region of a device and are not
intended to limit the scope of the invention.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
All methods described herein can be performed in a suitable order
unless otherwise indicated herein or otherwise clearly contradicted
by context. The use of any and all examples, or exemplary language
(e.g., "such as"), is intended merely to better illustrate the
invention and does not pose a limitation on the scope of the
invention unless otherwise claimed. No language in the
specification should be construed as indicating any non-claimed
element as essential to the practice of the invention as used
herein.
Hereinafter, embodiments are described referring to drawings.
The piezoelectric nanowire structure according to an embodiment of
the invention is described with reference to FIG. 1A and FIG. 1B.
FIG. 1A is a cross-sectional view showing an embodiment of the
piezoelectric nanowire structure, according to the invention, and
FIG. 1B is a cross-sectional view showing an embodiment of the
operation of the piezoelectric nanowire structure in FIG. 1A.
As shown in FIG. 1A, the piezoelectric nanowire structure includes
a base substrate 110, a plurality of a piezoelectric nanowire 210
disposed directly on the base substrate 110, and a piezoelectric
organic material layer 310 covering the plurality of piezoelectric
nanowires 210. In an embodiment, the plurality of a piezoelectric
nanowire 210 may be grown directly on the base substrate 110. The
piezoelectric nanowires 210 includes a base portion and a plurality
of a protruding portion extending directly from the base portion,
such that the piezoelectric nanowires 210 collectively form a
single unitary indivisible element.
In FIG. 1A, the piezoelectric organic material layer 310 contacts
an entire of upper and side surfaces of the plurality of a
piezoelectric nanowire 210. The piezoelectric organic material
layer 310 is disposed in an entire area between adjacent protruding
portions of the piezoelectric nanowires 210. On the upper surfaces
of the piezoelectric nanowires 210, the piezoelectric organic
material layer 310 may extend across areas between the adjacent
protruding portions of the piezoelectric nanowires 210, such that
the piezoelectric organic material layer 310 is effectively
planarized on the upper surfaces of the piezoelectric nanowires
210.
The base substrate 110 may be an inorganic material such as glass
or silicon (Si), or a polymer material such as polyethylene
terephthalate ("PET"), polyethylene sulfone ("PES"), and the like.
In addition, the base substrate 110 may be coated with a conductive
material such as a metal, a metal oxide, carbon nanotubes ("CNT"),
graphene, and the like on the insulator material. The base
substrate 110 may be transparent and flexible.
The piezoelectric nanowires 210 may include an inorganic material.
The inorganic material of the piezoelectric nanowires 210 may
include zinc oxide (ZnO), lead zirconate titanate ("PZT"), barium
titanate (BaTiO.sub.3), lead titanate (PbTiO.sub.3), aluminum
nitride ("AIN"), gallium nitride ("GaN"), or silicon carbide
("SiC"), or one of other piezoelectric materials, or combinations
of at least two thereof.
In one embodiment, the piezoelectric material for piezoelectric
nanowires 210 may have semiconductor characteristics. In one
embodiment, for example, piezoelectric nanowires 210 including
undoped zinc oxide (ZnO) have n-type semiconductor
characteristics.
The piezoelectric organic material layer 310 covering the
piezoelectric nanowires 210 may be an insulating piezoelectric
organic material such as polyvinylidene fluoride ("PVDF"), or a
composite material including an organic material having
semiconductor characteristics such as poly(3-hexylthiophene)
(P3HT), polyaniline, polypyrrole, poly(p-phenylene vinylene)
("PPV"), polyvinylene, polyacetylene, polythiophene, and
derivatives thereof.
The piezoelectric organic material layer 310 may be disposed on and
laminated on the piezoelectric structure, in accordance with
various methods such as spin coating, dip coating, sputtering,
e-beam evaporation, thermal evaporation, and the like.
As shown in FIG. 1B, when the piezoelectric nanowire structure is
pressed from an outside of the piezoelectric nanowire structure,
the piezoelectric nanowires 210 in the piezoelectric nanowire
structure are compressed in an applied direction of the force
pressing the piezoelectric nanowire structure. Since the
piezoelectric organic material layer 310 extends across areas
between the adjacent protruding portions of the piezoelectric
nanowires 210, when being pressed from the outside, the plurality
of piezoelectric nanowires 210 tend to be collectively deformed
under the influence of the unitary indivisible piezoelectric
organic material layer 310.
In the illustrated embodiment of FIGS. 1A and 1B, the piezoelectric
organic material layer 310 covering the piezoelectric nanowire 210
protects, and reduces or effectively prevents damage to the
piezoelectric nanowires 210, such as being broken. In addition, the
piezoelectric characteristics of the piezoelectric nanowire
structure are improved by the piezoelectric characteristics of the
piezoelectric organic material layer 310.
Hereinafter, the piezoelectric nanowire structure according to
another embodiment is described with reference to FIG. 2A and FIG.
2B. FIG. 2A is a cross-sectional view showing another embodiment of
a piezoelectric nanowire structure, according to the invention, and
FIG. 2B a cross-sectional view showing an embodiment of the
operation of the piezoelectric nanowire structure in FIG. 2A.
As shown in FIG. 2A, the piezoelectric nanowire structure according
to the illustrated embodiment is similar to the piezoelectric
nanowire structure shown in FIG. 1A.
The piezoelectric nanowire structure in FIG. 2A includes a base
substrate 110, a plurality of a piezoelectric nanowire 210 disposed
directly on the base substrate 110, and a piezoelectric organic
material layer 310 coated on the surface of the plurality of
piezoelectric nanowires 210. In an embodiment, the plurality of a
piezoelectric nanowire 210 may be grown directly on the base
substrate 110. The piezoelectric nanowires 210 includes a base
portion and a plurality of a protruding portion extending directly
from the base portion, such that the piezoelectric nanowires 210
collectively form a single unitary indivisible element.
In FIG. 2A, lower surfaces of the piezoelectric organic material
layer 310 contacts an entire of an upper and side surfaces of the
plurality of a piezoelectric nanowire 210. The piezoelectric
organic material layer 310 is only disposed at a predetermined
distance from the upper and side surfaces of the plurality of a
piezoelectric nanowire 210. In an area between adjacent protruding
portions of the piezoelectric nanowires 210, upper surfaces of the
piezoelectric organic material layer 310 are spaced apart from each
other, where no material of the piezoelectric organic material
layer 310 is disposed.
The piezoelectric nanowires 210 may include zinc oxide (ZnO), lead
zirconate titanate ("PZT"), barium titanate (BaTiO.sub.3), lead
titanate (PbTiO.sub.3), aluminum nitride ("AIN"), gallium nitride
("GaN"), or silicon carbide ("SiC"), or one of other piezoelectric
materials, or a combination of at least two thereof.
In one embodiment, the piezoelectric material for piezoelectric
nanowires 210 may have semiconductor characteristics. In one
embodiment, for example, the piezoelectric nanowires 210 including
undoped zinc oxide (ZnO) may have n-type semiconductor
characteristics.
The piezoelectric organic material layer 310 covering the
piezoelectric nanowires 210 may include an insulating piezoelectric
organic material such as polyvinylidene fluoride ("PVDF"), or a
composite material including an organic material having
semiconductor characteristics such as poly(3-hexylthiophene)
(P3HT), polyaniline, polypyrrole, poly(p-phenylene vinylene)
("PPV"), polyvinylene, polyacetylene, polythiophene, and
derivatives thereof.
The piezoelectric organic material layer 310 may be disposed on and
laminated on the piezoelectric structure, in accordance with
various methods such as spin coating, dip coating, sputtering,
e-beam evaporation, thermal evaporation, and the like.
However, differing from the piezoelectric nanowire structure shown
in FIG. 1A, the piezoelectric organic material layer 310 of a
piezoelectric nanowire structure according to the illustrated
embodiment in FIG. 2A is coated only a defined distance from the
surfaces of the piezoelectric nanowires 210, and is space apart in
areas between adjacent piezoelectric nanowires 210. Thereby, when
being pressed from the outside, the plurality of piezoelectric
nanowires 210 tend to be individually deformed.
As shown in FIG. 2B, when the piezoelectric nanowire structure is
pressed from the outside, the piezoelectric nanowires 210 in the
piezoelectric nanowire structure are compressed in the upper or
lower directions, or compressed or extended while moving in right
or left directions. In the illustrated embodiment of FIGS. 2A and
2B, the piezoelectric organic material layer 310 coated on the
surface of piezoelectric nanowire 210 protects, and reduced or
effectively prevents damage to the piezoelectric nanowires 210. In
addition, the piezoelectric characteristics of the piezoelectric
nanowire structure is improved by the piezoelectric characteristics
of the piezoelectric organic material layer 310.
A piezoelectric nanowire structure according to further embodiments
is described with reference to FIG. 3A and FIG. 3B. FIG. 3A and
FIG. 3B are cross-sectional views showing a piezoelectric nanowire
structure according to further embodiments.
As shown in FIG. 3A, the piezoelectric nanowire structure according
to a further embodiment is similar to the piezoelectric nanowire
structure shown in FIG. 1A.
The piezoelectric nanowire structure according to the illustrated
embodiment in FIG. 3A includes a base substrate 110, a plurality of
a piezoelectric nanowire 210 disposed directly on the base
substrate 110, and a piezoelectric organic material layer 310
covering the plurality of piezoelectric nanowires 210. In an
embodiment, the plurality of a piezoelectric nanowire 210 may be
grown directly on the base substrate 110. The piezoelectric
nanowires 210 includes a base portion and a plurality of a
protruding portion extending directly from the base portion, such
that the piezoelectric nanowires 210 collectively form a single
unitary indivisible element.
The piezoelectric nanowires 210 may include zinc oxide (ZnO), lead
zirconate titanate ("PZT"), barium titanate (BaTiO.sub.3), lead
titanate (PbTiO.sub.3), aluminum nitride ("AIN"), gallium nitride
("GaN"), or silicon carbide ("SiC"), or one other piezoelectric
material, or at least one or combinations of at least two
thereof.
In one embodiment, the piezoelectric material for piezoelectric
nanowires 210 may have semiconductor characteristics. In one
embodiment, for example, the piezoelectric nanowires 210 including
undoped zinc oxide (ZnO) may have n-type semiconductor
characteristics.
The piezoelectric organic material layer 310 covering the
piezoelectric nanowires 210 may be an insulating piezoelectric
organic material such as polyvinylidene fluoride ("PVDF"). The
insulating piezoelectric organic material may be also include a
composite material including an organic material having
semiconductor characteristics such as poly(3-hexylthiophene)
(P3HT), polyaniline, polypyrrole, poly(p-phenylene vinylene)
("PPV"), polyvinylene, polyacetylene, polythiophene, and
derivatives thereof.
However, differing from the piezoelectric nanowire structure shown
in FIG. 1A, the piezoelectric nanowires 210 of the piezoelectric
nanowire structure according to the illustrated embodiment are
etched to provide an uneven surface. That is, the upper and side
surfaces of the piezoelectric nanowires 210 are not entirely
planar, and include projections and recesses forming a profile of
the upper and the side surfaces. Thereby, contact characteristics
with the piezoelectric organic material layer 310 covering the
piezoelectric nanowires 210 are improved. The interface contact
area of a piezoelectric inorganic material layer of the
piezoelectric nanowires 210 and the piezoelectric organic material
layer 310 is increased to improve the electrical characteristics,
and to induce the piezoelectric inorganic material to be deformed
by the external force, so as to improve piezoelectric
characteristics.
As shown in FIG. 3B, an inside of the piezoelectric nanowires 210
of the piezoelectric nanowire structure according to the
illustrated embodiment is etched in a tube shape. Each of the
individual nanowires 210 includes a base portion, and a tubular
protruding portion extending directly from the base portion. The
piezoelectric organic material layer 310 is disposed in a area
within the tubular protruding portion of a nanowire 210, and
between adjacent individual nanowires 210. The piezoelectric
organic material layer 310 directly contacts an upper surface of
the base substrate 110, where the piezoelectric organic material
layer 310 does not contact the base substrate 110 in FIGS. 1A-3A.
While each of the individual nanowires 210 is a single unitary
indivisible member, the nanowires 210 are separated from each other
along the base substrate 110.
Thereby, the interface contact area of the piezoelectric inorganic
material layer of the piezoelectric nanowires 210 and the
piezoelectric organic material layer 310 is increased, so the
electronic characteristics are improved and the piezoelectric
inorganic material is easily deformed by the external force, so as
to improve the piezoelectric characteristics.
An electronic device including the piezoelectric nanowire structure
according to an embodiment of the invention, will now be described
with reference to FIG. 4 to FIG. 6. FIG. 4 is a cross-sectional
view schematically showing an embodiment of an electrical energy
generating device including a piezoelectric nanowire structure
according to the invention, FIG. 5 is a cross-sectional view
theoretically showing an embodiment of a first operation of the
electrical energy generating device shown in FIG. 4, and FIG. 6 is
a cross-sectional view theoretically showing an embodiment of a
second operation of the electrical energy generating device shown
in FIG. 4.
As shown in FIG. 4, the illustrated embodiment of the electronic
device including a piezoelectric nanowire structure according to
the invention is an electrical energy generating device including a
lower substrate 100 and an upper substrate 200 facing each other, a
piezoelectric nanowire structure 300 disposed between the lower
substrate 100 and the upper substrate 200, a connecting part 401
electrically connecting the lower substrate 100 and the upper
substrate 200, and a storing part 402 electrically and/or
physically connected to the connecting part 401. The piezoelectric
nanowire structure 300 may be disposed on the lower substrate
100.
The lower substrate 100 includes a first substrate 101 and a first
electrode 102 disposed on the first substrate 101, and the upper
substrate 200 includes a second substrate 201 and a second
electrode 202 disposed on the second substrate 201. The first
substrate 101 and the second substrate 201 may be flexible and
transparent. Although it is not shown, a blocking layer and/or a
transport layer may be disposed on the first electrode 102 and/or
the second electrode 202 in order to accelerate electrons and holes
to transport in one direction. In one embodiment, for example, a
molybdenum oxide ("MoOx") layer may be coated on the second
electrode 202 to inhibit transporting electrons, and to improve
transporting holes, so that only holes are selectively transported
to the second electrode 202.
Since the first substrate 101 and the second substrate 201 may
include a flexible material such as plastic, the shape of the first
substrate 101 and the second substrate 201 may be changed depending
upon applying external pressure to the piezoelectric nanowire
structure 300.
The first electrode 102 may include indium tin oxide ("ITO"),
carbon nanotubes ("CNT"), graphene, a transparent conductive
polymer, or one of other appropriate materials or combinations of
at least two thereof. The second electrode 202 may include gold
(Au), a gold-palladium alloy ("AuPd"), palladium (Pd), platinum
(Pt), ruthenium (Ru), or one of other appropriate metals or
combinations of at least two thereof. At least one of the first
electrode 102 and the second electrode 202 may include a flexible
electrode that is capable of being deformed by the applied
pressure.
The first electrode 102 and the second electrode 202 are physically
and/or electrically connected by the connecting part 401. The
connecting part 401 may include a conductive material.
The piezoelectric nanowire structure 300 includes a plurality of a
piezoelectric nanowire 301 including an inorganic material, and a
piezoelectric organic material layer 302 covering the plurality of
piezoelectric nanowires.
The piezoelectric nanowire 301 includes an inorganic material
having piezoelectric characteristics, and the inorganic material
may include zinc oxide (ZnO), lead zirconate titanate (PZT), barium
titanate (BaTiO.sub.3), lead titanate (PbTiO.sub.3), aluminum
nitride ("AIN"), gallium nitride ("GaN"), or silicon carbide
("SiC"), or one of other appropriate piezoelectric materials or a
combination of at least two thereof. In the illustrated embodiment,
the piezoelectric material for piezoelectric nanowires 301 may have
semiconductor characteristics. In one embodiment, for example,
piezoelectric nanowires 301 including undoped zinc oxide (ZnO) may
have n-type semiconductor characteristics.
The piezoelectric organic material layer 302 may have photoelectric
conversion characteristics. The piezoelectric organic material
layer 302 may include a p-type organic semiconductor generating
electron-hole excitons by adsorbing light such as sunlight.
Particularly, the piezoelectric organic material layer 302 may
include poly(3-hexylthiophene) (P3HT).
A plurality of piezoelectric nanowires 301 may be disposed directly
on and contacting the first electrode 102. In one embodiment, the
plurality of piezoelectric nanowires 301 may be grown directly on
the first electrode 102. When the plurality of piezoelectric
nanowires 301 are disposed on the first electrode 102, instead of
being directly providing on the first substrate 101, it is easy to
control the growth of the piezoelectric nanowires 301. In one
embodiment, for example, the piezoelectric nanowires 301 may be
grown in a direction perpendicular to a plane of the first
electrode 102, and the shape or direction of each piezoelectric
nanowire 301 becomes more uniform.
Alternatively, a conductive zinc oxide (ZnO) thin film may be grown
on the first substrate 101 before growing the piezoelectric
nanowires 301, and the zinc oxide thin film may act as the first
electrode 102. The grown zinc oxide thin film would be disposed
directly between the first substrate 101 and the piezoelectric
nanowires 301.
The protruding portions of the piezoelectric nanowires 301 may
longitudinally extend in a direction perpendicular to the surface
of the first electrode 102 and the second electrode 202. In an
alternative embodiment, the piezoelectric nanowire 301 may
longitudinally extend in a slanted direction with respect to the
surface the first electrode 102 and the second electrode 202,
instead of a perpendicular direction. The number of piezoelectric
nanowires 301 shown in the figures is illustrated only as an
embodiment, but it is clear that the number and allocation of
piezoelectric nanowires 301 may be different depending upon the
size and the usage of the device.
Hereinafter, the operation of the electrical energy generating
device shown in FIG. 4 is described with reference to FIG. 5 and
FIG. 6. FIG. 5 is a cross-sectional view theoretically showing an
embodiment of a first operation of the electrical energy generating
device shown in FIG. 4, and FIG. 6 is a cross-sectional view
theoretically showing an embodiment of a second operation of the
electrical energy generating device shown in FIG. 4.
First, the first operation when the electrical energy generating
device including the piezoelectric nanowire structure is applied
with pressure is described with reference to FIG. 5.
When the electrical energy generating device is applied with
pressure, the second substrate 201 and the second electrode 202 may
be bent downward at a position (A) where the pressure is applied.
According to bending the second substrate 201 and the second
electrode 202 downward, the distance between the first electrode
102 and the second electrode 202 is decreased, so the piezoelectric
nanowires 301 and the piezoelectric organic material layer 302
disposed at the position (A) may be compressed and deformed.
Thereby, the deformed piezoelectric nanowires 301 and piezoelectric
organic material layer 302 exhibit piezoelectric effects. That is,
each part of the piezoelectric nanowires 301 and piezoelectric
organic material layer 302 has a predetermined potential depending
upon the applied compression pressure or tensile stress. The
piezoelectric organic material layer 302 covering the piezoelectric
nanowires 301 may protect, and reduce or effectively prevent
damage, such as breaking, of the piezoelectric nanowires 301. In
addition, the piezoelectric characteristic of the piezoelectric
nanowire structure is improved by the piezoelectric characteristics
of the piezoelectric organic layer 302.
Electrons 503 generated by the piezoelectric effects of the
piezoelectric nanowires 301 and the piezoelectric organic material
layer 302 are transported to the first electrode 102 or the second
electrode 202, so the electrical energy is generated.
The electrical energy generated by the piezoelectric nanowires 301
and the piezoelectric organic material layer 302 may be stored in
the storing part 402. In addition, the electrical energy generating
device may include a converter (not shown) for converting
alternating current ("AC") to direct current ("DC") when the
electrical energy is generated as AC.
The storing part 402 may include a rechargeable battery, a
capacitor, or other appropriate electrical energy storing element,
for example, a nickel-cadmium battery, a nickel-hydrogen battery, a
lithium ion battery, or a lithium polymer battery. In addition, the
storing part 402 may further include an amplifier (not shown) for
amplifying a voltage.
FIG. 5 exemplarily shows the case in which the second substrate 201
and the second electrode 202 are bent by applying pressure to the
electrical energy generating device, but the same effect is gained
in the case that the pressure is applied to the first electrode 102
or in the case in which the pressure is applied to both the first
electrode 102 and the second electrode 202. In other words, the
electrical energy is generated by pressing or bending the
electrical energy generating device.
An embodiment of a second operation in which the electrical energy
generating device including a piezoelectric nanowire structure
absorbs light such as sunlight will now be described with reference
to FIG. 6.
When the electrical energy generating device is irradiated with
light such as sunlight, a part or all of the irradiated light
arrives at the piezoelectric nanowire structure 300. If electrons
included in the piezoelectric nanowire structure 300 absorb energy
from the irradiated light, exited electron-hole pairs (excitons)
may be provided through photoelectric conversion characteristics of
the piezoelectric organic material layer 302 covering the
piezoelectric nanowires 301. The electron-hole pairs (excitons) may
be separated into electrons 501 and holes 502 in the interface
between the p-type piezoelectric organic material layer 302 and the
n-type piezoelectric nanowires 301. The separated electrons 501 are
transported to an anode which is the first electrode 102 along with
the n-type piezoelectric nanowires 301, and holes 502 are
transported to a cathode which is the second electrode 202 along
with the piezoelectric organic material layer 302.
In the illustrated embodiment in FIG. 6, the sunlight is irradiated
from the lower side of the electrical energy generating device, but
the sunlight may be irradiated from the upper side of the
electrical energy generating device. When the sunlight is
irradiated from the upper side of the electrical energy generating
device, the plurality of piezoelectric nanowires 301 induce the
effect of concentrating the irradiated light to improve the
electrical energy generating efficiency of the piezoelectric
nanowire structure 300.
Electrons 501 are transported to the first electrode 102 and holes
502 are transported to the second electrode 202, such that a
current may flow through a closed circuit including the first
electrode 102 and the second electrode 202 that are connected by
the connecting part 401 and the piezoelectric nanowire structure
300. The connecting part 401 is electrically connected with the
storing part 402, so the electrical energy generated by the
piezoelectric nanowire structure 300 may be stored in the storing
part 402.
Thereby, the piezoelectric organic material layer 302 of the
piezoelectric nanowire structure may have photoelectric conversion
characteristics. Accordingly, the electrical energy generating
device including a piezoelectric nanowire structure 300 may
generate electrical energy not only by applying pressure to the
piezoelectric nanowires using the piezoelectric phenomenon, but
also by using light such as sunlight or the like.
Many of characteristics of the piezoelectric nanowire structure
shown in FIG. 1A to FIG. 3B may be applied to the piezoelectric
nanowire structure 300 included in the electronic device shown in
FIG. 4.
Hereinafter, the electronic device including the piezoelectric
nanowire structure according to another embodiment is described
with reference to FIG. 7. FIG. 7 is an exploded perspective view
showing the electronic device including the piezoelectric nanowire
structure according to another embodiment.
The electronic device shown in FIG. 7 is similar to the electronic
device shown in FIG. 4. Particularly, the composition and functions
of the first substrate 101, the second substrate 201, and the
piezoelectric nanowire structure 300 of the electronic device shown
in FIG. 4 are similar to those of the electronic device shown in
FIG. 7, so a detailed description thereof is omitted.
However, differing from the electronic device shown in FIG. 4, the
first electrode 102 and the second electrode 202 of the electronic
device shown in FIG. 7 are multiply divided. The collective first
electrode 102 longitudinally extends in a second direction D3 on
the first substrate 101, and includes a plurality of first
sub-electrodes 102a, 102b, and 102c arranged spaced apart from each
other in the second direction D3. Each of the first sub-electrodes
102a, 102b, and 102c longitudinally extends in a first direction
D2.
The collective second electrode 202 longitudinally extends in the
first direction D2 perpendicular to the second direction D3 on the
second substrate 201, and includes a plurality of second
sub-electrodes 202a, 202b, and 202c arranged spaced apart from each
other along the first direction D2. Each of the second
sub-electrodes 202a, 202b, and 202c longitudinally extends in the
second direction D3.
First electrode 102 and second electrode 202 respectively including
the plurality of first sub-electrodes 102a, 102b, and 102c and the
plurality of second sub-electrodes 202a, 202b, and 202c, may be
arrayed in a matrix. That is, the first electrode 102 and second
electrode 202 may be arranged overlapping each other, in a plan
view of the device, such that at least a portion of the first
sub-electrodes and the plurality of second sub-electrodes are
arranged overlapping each other. The number of first sub-electrodes
102a, 102b, and 102c and second sub-electrodes 202a, 202b, and 202c
shown in FIG. 7 is one embodiment, and is not limited thereto. The
numbers may be different depending upon the size and usage of the
device.
When employing the electronic device including the first electrode
102 and the second electrode 202 disposed to form a matrix array,
it is possible to sense a position of the device where pressure is
applied, by sensing where current flows among the plurality of
first sub-electrodes 102a, 102b, and 102c and sensing where current
flows among the plurality of second sub-electrodes 202a, 202b, and
202c. Accordingly, it is also possible to sense the position of the
device where the pressure is applied when the electronic device is
applied as a touch sensor or the like. In addition, it is possible
to develop a multi-functional device simultaneously accomplishing
sensing of pressure and generating energy.
In the electronic device shown in FIG. 7, a plurality of the
piezoelectric nanowire 301 is disposed on each of the first
sub-electrodes. The piezoelectric nanowires 301 may be disposed on
substantially an entire of an upper surface of the first
sub-electrodes as shown in FIG. 7. Alternatively, in the electrical
energy generating device according to another embodiment, the
piezoelectric nanowires 301 may be disposed only in a region where
the first electrode 102 crosses the second electrode 202 in the
plan view of the device.
In addition, in the electronic device shown in FIG. 7, the first
electrode 102 and the second electrode 202 longitudinally extend
along directions perpendicular to each other, but this is one
embodiment. Alternatively, in the electrical energy generating
device according to another embodiment, the second electrode 202
may extend at an angle to the second direction D3 in which the
first electrode 102 is extended.
Many of characteristics of the piezoelectric nanowire structure
shown in FIG. 1A to FIG. 3B may be applied to the piezoelectric
nanowire structure included in the electronic device shown in FIG.
7.
In addition, many characteristics of the electrical energy
generating device shown in FIG. 4 to FIG. 6 may be applied to the
electronic device shown in FIG. 7.
While this disclosure has been described in connection with what is
presently considered to be practical embodiments, it is to be
understood that the invention is not limited to the disclosed
embodiments, but, on the contrary, is intended to cover various
modifications and equivalent arrangements included within the
spirit and scope of the appended claims.
* * * * *